Advances in semiconductor technology have succeeded in reducing the size of and driving down the cost of portable electronic devices to the point that display devices have become a limiting factor in the development of inexpensive and reliable portable devices. Today, most portable systems and laptop computers utilize Active Matrix Liquid Crystal technology for the display. However, such displays have several shortcomings. The most notable of these are limited viewing angles, high cost and high power consumption compared to the portable system""s other semiconductor electronics. Cathode Ray Tube (CRT) Technology which has been used for larger computer systems enjoys some advantages over liquid crystal systems such as wide viewing angles. However CRT""s have been too bulky for integration into portable devices and also require significant amounts of power for operation.
Field Emission Display (FED) technology has been proposed as a display technology that enjoys the advantages of allowing for wide viewing angles as well as being thin and light weight. Field emission displays utilize cold electron emitters called nanotips to eject electrons onto a luminescent surface, typically a phosphor surface such as those found on CRTs. Thus the viewing surface of the FED enjoys many of the advantages, including wide viewing angle of CRTs. Using nanotips rather then an electron gun tube as an electron source significantly reduces power consumption of the display device. The use of nanotip electron sources also reduces the form factor of the display. Electrons ejected from the nanotip typically propagate through a vacuum space within the display toward the nearby luminescent surface. When the electrons impact the luminescent surface, light is emitted. A driving circuit controls the pattern displayed by controlling the nanotip emission of electrons.
One problem with such field emission devices is that the fabrication of nanotips is expensive and difficult. Furthermore, the large size of current nanotips requires higher voltages for operation of the FED than is desirable. Thus, an improved method of forming small nanotips is needed.
The present invention relates to an improved nanotip and an improved method of forming the nanotip. The nanotip is formed from a defect or dislocation in a semiconductor material. The dislocation forms in a direction preferably perpendicular to the interface of the semiconductor and a substrate. The dislocation is selectively etched to produce a nanotip which is subsequently used as an electron source.